This invention relates to a compressed gas utilization system and method and, more particularly, to such a system and method in which the compressed gas is stored in a sub-sea environment and later utilized as energy.
Compressed air energy storage (CAES) systems are generally known, and are for the purpose of storing energy, in the form of compressed gas, and later utilizing this stored potential energy for such purposes as the generation of electrical power. Typically, the CAES systems use electrical power purchased at low cost during off-peak periods to compress gas for storage. During periods of peak power demand, the potential energy in the stored gas is used to produce electrical power, which may be sole at a premium rate.
These systems can be used in a stand-alone mode for generating electrical power connected in a power grid, or they can be used with a conventional electrical power generating plant connected in a power grid, or the like. In the latter case, the power generated by the CAES system can be utilized as an adjunct to the power normally generated by the conventional power generating plant, usually during relatively high load conditions. CAES systems can also be used for balancing, optimizing, and enhancing the reliability of power grids and associated base-loaded power generating plants. Also, CAES systems can create spinning reserves or standby generating capacity, and can come on line in a relatively short time to take up a power load in the event a power generating plant on the grid malfunctions. Further, CAES systems can balance the power grid by taking and saving excess power, and can make up extra demand without a ramp up required by conventional power generating plants. Still further, CAES systems can improve the availability of renewable resource power by storing excess power and generating power when the renewable resource power is unavailable or inadequate.
A typical CAES system, or plant, includes a compression train in which a motor-driven compressor compresses a gas, such as air. The compressed gas is then transferred to, and stored at, a storage site, usually at a remote location, for later use at which time it is transferred back to an expansion side of the CAES plant. During the expansion cycle, the compressed gas is expanded through a conventional expansion train that may include high pressure and/or low pressure turbines that drive an electrical power generator to generate electrical power. In these arrangements, a fuel gas is often burned with the expanding gas to raise the temperature of the gas and improve the efficiency of the system
However, known CAES plants utilize underground storage facilities for the compressed gas, along with piping systems to connect the storage facility to the compression and expansion sides of the CAES plant. This severely limits the site location due to the dependence on an acceptable geology for underground storage location. Also, the underground storage facility is usually located a considerable distance from the power generation or power consumption areas, resulting in transmission costs, losses and related expenses. Furthermore, underground storage facilities are susceptible to earthquake damage.
Therefore what is needed is a system of the above type for storing the gas that avoids the above problems. To this end, an embodiment of the present invention is directed to a sub-sea energy storage system which provides a significant improvement over the previous systems.